ROTORK /YCT  YT-3100  Series - YT-3100RDN5211S

The YT-3100 smart positioner controls a pneumatic valve by receiving a 4-20 mA DC signal from a controller and using its internal microprocessor to precisely adjust the valve's position. It works by using a non-contact sensor for accurate feedback, performing auto-calibration for optimal performance, and executing intelligent control algorithms to maintain the desired valve position even with fluctuations in supply pressure. The device uses compressed air to move the actuator, converting the electrical input signal into precise pneumatic output. 

Working principle

• Input signal: The YT-3100 receives a 4-20 mA DC current signal from a control system.  Signal processing: A high-performance microprocessor interprets the input signal. 
• Actuation: The microprocessor sends signals to a pneumatic actuator, which uses compressed air to open or close the valve.
• Feedback: A non-contact sensor provides constant feedback on the valve's actual position to the microprocessor. 
• Correction: The microprocessor continuously compares the desired position (from the input signal) to the actual position (from the sensor) and makes adjustments to the pneumatic output to correct any discrepancies, ensuring precise control. 
• Intelligent features: The device includes functions like auto-calibration and optimal PID control to improve stability and efficiency.  Output: The positioner can also provide a 4-20 mA analogue output signal for process monitoring. 

Operating principle

The working principle of the YT-3100 involves the integration of several core components:

1. Signal input (4–20 mA DC): The process control system sends a 4–20 mA electrical current to the positioner, representing the desired valve position (e.g., 4 mA is 0% open, 20 mA is 100% open).
2. Microprocessor and PID control: The microprocessor computes the difference between the desired position (from the electrical signal) and the actual valve position (from the feedback sensor). Based on this error, the microprocessor performs a Proportional-Integral-Derivative (PID) calculation to determine the necessary output correction.
3. I/P converter and pilot valve: The signal from the microprocessor is sent to an internal I/P (current-to-pressure) converter. This module, which may use a flapper/nozzle or torque motor assembly, converts the electrical signal into a small, proportional pneumatic signal.
4. Pneumatic volume booster: This output from the I/P converter is amplified by a high-flow volume booster to provide enough air pressure and volume to move the much larger pneumatic valve actuator quickly and accurately.
5. Actuator and valve: The boosted air pressure is sent to the actuator, causing it to change the position of the valve. The YT-3100 is designed for both linear (sliding-stem) and rotary (quarter-turn) type actuators.
6. Non-contact position sensing: A key feature of the YT-3100 is its non-contact position sensor, which detects the actual position of the valve stem or shaft. This eliminates the friction and wear found in older mechanical linkages, improving performance and extending the product's lifetime.
7. Feedback loop: The actual position from the non-contact sensor is fed back into the microprocessor. The processor continuously repeats the comparison and adjustment cycle, ensuring the valve remains at the precise position commanded by the 4–20 mA input signal, even if supply pressure or other conditions change.

Key features enhancing the working principle

• Auto-calibration: A simplified auto-calibration feature allows for easy and accurate initial setup by using the embedded microprocessor to automatically map the electrical input signal to the valve's physical stroke.
• Advanced functions: The smart management system includes advanced functions such as optimal PID control and the ability to set different flow characteristics, such as linear, equal percentage (EQ%), or quick open.
• Rapid response: With a fast calculation speed, the YT-3100 provides quick, responsive, and stable control, minimizing valve position changes during events like a temporary power failure.

 Full Datasheet

Positioner Transmitter Feature   YT-3100RDN5211S

Basic Ordering Information